Within his own specialised field he has given information which has been a considerable help in estimating the performance of one of the radars of the Moscow ABM system”. But, why was defeating the Moscow ABM system of such importance to the UK? These would be launched with the intention of reaching the atmosphere and carrying out a megaton sized nuclear detonation to wipe out incoming nuclear warheads. Before they entered service though, events happened which nearly dramatically changed the story of the British nuclear deterrent force forever. © Crown copyrightHistory thankfully records that for all the UK concerns, GPALS was to quickly cease to be a security concern.